cmd

pkg/hex.go

@@ -0,0 +1,32 @@
+package imageutils
+
+import (
+	"fmt"
+	"image/color"
+	"errors"
+)
+
+var ParseHexColorErr = errors.New("invalid length, must be 7 or 4")
+
+func ParseHexColor(s string) (c color.RGBA, err error) {
+	c.A = 0xff
+	switch len(s) {
+	case 7:
+		_, err = fmt.Sscanf(s, "#%02x%02x%02x", &c.R, &c.G, &c.B)
+	case 4:
+		_, err = fmt.Sscanf(s, "#%1x%1x%1x", &c.R, &c.G, &c.B)
+		// Double the hex digits:
+		c.R *= 17
+		c.G *= 17
+		c.B *= 17
+	default:
+		err = ParseHexColorErr
+
+	}
+	return
+}
+
+func ColorToHex(c color.Color) string {
+	r, g, b, _ := color.NRGBAModel.Convert(c).RGBA()
+	return fmt.Sprintf("#%02x%02x%02x", byte(r), byte(g), byte(b))
+}

pkg/hex_test.go

@@ -0,0 +1,47 @@
+package imageutils
+
+import (
+	"fmt"
+	"image/png"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// Returns path of first occured file
+// with png extension in user's home directory.
+func firstPNG(root string) (filename string,
+	err error) {
+	var fn filepath.WalkFunc = func(path string,
+		info os.FileInfo,
+		fileErr error) error {
+		if fileErr != nil {
+			return fileErr
+		}
+		if !info.IsDir() &&
+			filepath.Ext(path) == ".png" {
+			filename = path
+			return nil
+		}
+		return nil
+	}
+	err = filepath.Walk(root, fn)
+	return
+}
+
+func TestColorToHex(t *testing.T) {
+	root := os.Getenv("HOME")
+	path, err := firstPNG(root)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f, err := os.Open(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	img, err := png.Decode(f)
+	if err != nil {
+		t.Fatal(err)
+	}
+	fmt.Println(ColorToHex(img.At(0, 0)))
+}